Brush construction



April 13, 1954 A. N. SOLBERG 2,674,759

BRUSH CONSTRUCTION Filed Sept. 10, 1948 2 Sheets-Sheet l i 7 YJ 8 5 6INVENTOR. 6120105 M 5OL8ER6 Patented Apr. 13, 1954 UNITED STATES ATENTOFFICE BRUSH CONSTRUCTION Application September 10, 1948, Serial No.48,631

6 Claims. '3

The invention relates to a brush of improved construction.

A continual problem in the brush making art is the difiiculty ofobtaining practical as-Well as attractive means for mounting the.bunches or tufts of bristles on a brush handle. Mechanical devices forbinding or clamping the bristle tufts to the handle are ordinarilyunsatisfactory because of the inevitable loosening of the clamp,whereupon the individual bristles fall or are pulled out of the tuft.The use of a cementitious agentto form a hardened body or matrix inwhich a tuft may be permanently cemented has been found to be the mostsatisfactory means for mounting the tuft on the brush handle.

The problem of the selectionof the most satisfactory cement has beengiven considerable at" tention in the art, but for many years animalglue has enjoyed practically uncontested prevalence as the cement formounting the. tuft on the handles of the brushes. While animal glue hasits shortcomings, it appeared that no other material could be usedsatisfactorily asa substitute. Practically all synthetic resins are moreexpensive than animal glue, and resins available in attractive, lightcolors are particularly expensive. Other resins are brittle or flexibleand must, therefore, be supported or reinforced, e. g., by a metalferrule. Still others are not sufiiciently resistant to water or to theorganic solvents used in paints.

Animal glue isan impure form of gelatin, being a typical organicnitrogenous colloidal substance of the protein class. It absorbs coldwater with much swelling and dissolves in hot water. It is athermoplastic substance. It exhibits great strength when used in theform of a thin adhesive film, but it is quite weak and brittle when usedin the form of a solid body or a layer of substantial thickness.Ordinarily, when used in fabrication of brushes, animal glue must besupportedand coveredas'much' as possible. The prevalent use of animalglue as a cement for brush bristles can be attributed mainly to the factthat none of the workers in the artehave been able to find a materialwhich is appreciably better than the glue.

Any synthetic resin which is to be used in preference to animal glue inthe fabrication of brushes must have substantially better properties tocompensate for the higher cost of the resin. As a rule, any syntheticresin which would be acceptable would have to be an infusible resin,,since an i-nfusible resin doesnot soften when warm and is not solublein water andJmost organic solvents. However, infusible resins in generalcan be formed only by the simultaneous application of heat and pressure.Thus, in the manufacture of a brush having the tuft. cemented in aninfusible resinous body, it is generally necessary to employ hotpressing equipment, which is very cumbersome and expensive, as well asimpractical in the brush making art.

Urea-formaldehyde resin is one of the most useful infusible resins,because it is colorless, resistant to light, resistant to water andorganic solvents, and relatively inexpensive. Moreover,urea-formaldehyde resin is unique among infusible resins in that it canbe produced without the application of heat, by gelling and hardening asolution of urea-formaldehyde condensation product by means of ahardening catalyst. After a solid body has been formed by hardening asolution of a urea-formaldehyde condensation product, however, the bodycracks and disintegrates in drying out. It is believed that thedisintegration of a body formed by hardening such a solution is due tothe colloidal nature of the solution. Evaporation of the solvent fromthe solution leaves a solid that is peculiarly lacking in structuralstrength and continuity.

The principal object of the invention is the fabrication, by inexpensivemethods, of a brush of superior durability having the tuft mounted in abinder comprising an infusible synthetic resin. More specific objectsand advantages are apparent from the description, in which reference ishad to the accompanying drawings illustrating brushes fabricated inaccordance with the invention.

Figure I of the drawings is a plan View of a brush embodying theinvention.

Figure II is a side elevaticnal view of the brush shown in Figure I.

Figure III is a plan view of an artists style brush embodying theinvention.

Figure IV is a side elevational View of another brush embodying theinvention.

Figure V is an enlarged vertical sectional view taken substantiallyalong the line V--V of Figure II.

Figure VI is an enlarged fragmentary plan view of the ferruled portionor the brush shown in Figure III, with part broken away and part shownin section.

Figure VII is a plan view of a paint brush embodying the invention withpart brokenaway and part shown in section,

Figure VIII is a plan view of a quill brush embodying the invention.

Figure IX is a plan view of another brush embodying the invention.

Figure X is a plan view of still another brush embodying the invention.

Figure XI is an enlarged vertical sectional view taken substantiallyalong the line XI-XI of Figure X.

These specific drawings and the specific disclosure that follows merelydisclose and illustrate the invention and are not intended to limit itsscope.

Referring to the drawings in detail, in Figures I and II, the handle Iof the brush illustrated consists of a manually grippable portion 2 atone end and a wedge-shaped portion 3 at the other end. A generallyhemi-cylindrically-shaped solid cement body 4 (see Figure V) is mountedon and adheres to each face of the wedge-shaped portion 3. Embedded ineach cement body 4 is the butt 5 of a bristle tuft 6 which extends fromone end of the cement body 4 outwardly to form a sword-like brush tip 1.Covering what would otherwise be the exposed portion of each cement bodyl is a layer of binder 8 integrated with the cement body 4 so as to be aperipheral portion thereof and to impregnate a peripheral portion of thebutt 5 of the tuft 6.

The solid cement body 4 may consist of any substance which can be usedto receive the butt 5 of the tuft 6 and penetrate therein so as tocontact and adhere to the basal portion of each bristle in the tuft Bwhen such substance has set to form a solid. Since one of the principaladvantages of the invention it is adaptability to inexpensive materials,it is not anticipated that the substance will be an expensive ingredientand the preferred substance is animal glue.

The bristle tuft ii is composed of camel hair.

Camel hair is the name given to hair obtained from a Siberian squirrel.The hairs are removed from the tail of the squirrel and heated to removethe kinks and to render the hairs resilient. The hairs so obtained taperto very fine ends and are particularly useful in paint brushes becausethey permit the drawing of extremely fine lines. Camel hair is preferredin the practice of the invention also because it has excellentabsorption properties, and the brushes illustrated in the drawingscontain camel hair bristles. However, any of the usual types of bristlesmay be used in the practice of the invention, including bristles fromanimals such as hogs and horses and synthetic bristles such as thosemade from nylon and cellulose acetate. When particularly smooth bristlessuch as those made from nylon are used, the basal portions of suchbristles preferably are sanded before being treated with thecementitious agent. Bristles from animals, i. e., animal hairs, arepreferred for use in the practice of the invention since they areusually very absorbent and thus may be readily impregnated with thebinder 8.

The first step in the fabrication of the brush illustrated in Figures I,II and V involves the cementing of the tuft 6 on the handle I using asubstance such as animal glue. This step may be carried out simply, forexample, by dipping the butt 5 of the tuft 6 in molten glue and thenplacing the butt 5 on the face of the wedgeshaped portion 3 of thehandle I and permitting the glue to set. The glue sets to form thegenerally hemi-cylindrically-shaped solid cement body 4. The next stepinvolves the application of the binder 8 of the invention so that itimpregnates a peripheral portion of the butt 5 of the tuft 6. The bindermay be applied in one or more coats.

The binder 8 comprises a hardened urea-formaldehyde condensationproduct. In accordance with the invention, the binder is applied byinoistening the peripheral portion of the cement body 4 with a solutionof a urea-formaldehyde condensation product and a hardener therefor. Thesolution penetrates the cement body t and impregnates a peripheralportion of the butt 5 of the tuft 6. The urea-formaldehyde condensationproduct then hardens to form a layer which includes the peripheralportion of the butt 5 of the tuft 6, as well as the peripheral portionof the cement body 4 which has been permeated with the solution of theurea-formaldehyde con-- densation product. It has been discovered thatthe layer of the binder 8 so formed does not crack and disintegrate likethe bodies heretofore prepared by gelling and hardening a solution of aurea-formaldehyde condensation product. In fact, contrary toexpectations, the layer of the hardened binder 8 gives great strength tothe cement body so that the cement does not crack or crumble during use,as it would if the cement body of, for example, animal glue were leftuncovered and unsupported. The binder 8 is bifunctional in that it formsa protective waterresistant covering for the cement body 4 and alsosupports and strengthens the cement body 4. It is believed that thefailure of the layer of hardened urea-formaldehyde condensation productto disintegrate results from the fact that the layer dries outappreciably during hardening of the reaction product.

The binder 8 may contain various modifying agents such as plasticizers,lubricants, opacifiers and pigments, as well as resins such asunsaturated polyesters (i. e., polybasic alcohol-polycarboxylic acidpolyesters) rosin-modified alkyds, ethyl cellulose and other syntheticresins. The foregoing ingredients may be used in solution with theurea-formaldehyde condensation product, or separately. As used hereinthe term binder means the infusible urea-formaldehyde condensationproduct and any of the foregoing modifying agents or resins which mayhave been added therewith. It has been found that the best results,particularly in strength, cannot be obtained if the binder does notconsist of at least 50 per cent by weight of infusible ureaformaldehydecondensation product. The preferred proportion in the binder is at leastabout per cent by weight of infusible urea-formaldehyde condensationproduct, and the optimum results are obtained using a binder consistingessentially of infusible urea-formaldehyde condensation product. Ofcourse, a certain amount of other ingredients such as the hardener orits decomposition products ordinarily are present in the infusiblebinder.

Although the solution with which the cement body 4 is moistened may be asolution of a ureaformaldehyde condensation product in any desiredsolvent such as an alcohol or an alcohol diluted by a hydrocarbon, themost economical solvent is water. The hardening catalyst may bedissolved in the solution before the cement body 4 is moistenedtherewith, or it may be applied in any other desired manner to cause itto dissolve after the cement body 4 has been moistened with thesolution.

The hardeners that are useful with urea-formaldehydecondensationproducts are acid substances such as acid salts and varioussubstances that liberate acids. Organic or inorganic acids may be used,but acid salts such as ammonium chloride are preferred.

The quantity of hardening agent employed depends upon-the speed ofhardening desired,-

and the speed of hardening should be so coordinated with the speed ofdrying that appreciable drying occurs during the hardening. Thus, when asufficient proportion of hardener is used to cause hardening to takeplace in one hour, the binder 8 must be applied in a thinner layer thanwhen the hardening requires, for example, 8 hours. The speed of drying,and'consequently the permissible thickness of the layer, will vary withthe relative humidity of the atmosphere and the porosity or theabsorbent char acteristics of the cement body and the bristles therein.The ratio of the binder 8 to the cement body 4 that can be employed willvary with the coarseness of the bristles and the texture of the cementbody.

In the preparation of an aqueous solution of a urea-formaldehydecondensation product for use in carrying out the invention, it ispreferable to carry the urea-formaldehyde condensationas far as it canbe carriedwithout precipitation. A suitable solution of aurea-formaldehyde condensation product may be prepared as follows:

Urea and formaldehyde in a molar ratio of 1:2 are gently refluxed in anaqueous solution that has been brought to a pH of 4.5-5.0 by means ofsodium hydroxide. After the refluxing has been continued long enough(about one hour) to carry the urea-formaldehyde condensation to thedesired stage, the solution is neutralized and evaporated under a vacuumto the desired concentration.

To facilitate storage or shipment, the ureaformaldehyde condensationproduct may be obtained in granules or powdered form by drum drying orspray drying the solution so prepared. If desired, the dry powder may beapplied to the peripheral portion of the cement body 4, and thenmoistened. However, it is preferable to redissolve the urea-formaldehydecondensation product so that a peripheral portion of the butt 5 of thetuft 6 may be better impregnated with the resulting solution. A solutionused for moistening the cement body 4 should be no more dilute thannecessary for convenient application to the surface of the cement body 4because a more dilute solution makes the material harder to dry.

The amount of the binder t which may be used in the practice of theinvention is simply the amount necessary to give the desired strengthand support to the cement body 4 so that the cement body 4 does notcrack or crumble during ordinary use of the brush. One of the aspects ofthe invention resides in the discovery that it is possible to obtainsuch a layer of infusible urea-formaldehyde condensation product whichdoes not crack or disintegrate. The amount of the binder 8 actually usedvaries with the size and shape of the cement body t, but this amount canbe determined readily by the worker in the art to suit his particularcase. Ordinarily, an amount of hardened binder 8 that is as little as3-5 per cent of the weight of the cement used may be used to obtainappreciable impregnation of a peripheral portion of the butt 5 of thetuft 6, i. e., to obtain appreciable improvement in strength and supportfor the ce ment body.

In actual practice, care must be taken in applying the solution of theurea-formaldehyde condensation product in order to avoid moistening anypart of the tuft 6 other than the butt 5. The portion of a tuft which isimpregnated with an infusible urea-formaldehyde condensation product isvery rigid, and therefore, should be confined to the butt 5. It isbelieved that in many cases, for example in brushes using camel hairbristles, a substantial proportion of the unaccounted for strength andsupport comes from the reenforcing effect of the impregnated bristles inthe peripheral portion of the butt 5 of the tuft 6.

Another embodiment of the invention involves the use of a fabricmaterial wrapped around the cement body 4 and impregnated with theinfusible binder. In such an embodiment of the invention added strengthand support is obtained from the stiffened impregnated'fabric materialas well as the impregnated bristles in the peripheral portion of thebutt 5 of the tuft 6. Also, the fabric material aids in drying out theurea-formaldehyde condensation product during hardening. An example ofthis embodiment of the invention is shown in Figure IX, whichillustrates a brush which is substantially the same as that shown inFigures I, II and V except that the cement bodies are wrapped with aserving 9, which consists of a cotton thread or yarn. The handle it ofthe brush illustrated consists of a manually grippable portion H at oneend and a wedge-shaped portion 12 at the other end. A generallyhemicylindrically-shaped solid cement body (covered by the serving 9) ismounted on and adheres to each face of the wedge-shaped portion l2.Embedded in each cement body is the butt [3 of a bristle tuft M, whichextends from one end of the cement body outwardly to form a dagger-likebrush tip I5. The serving 5 is wound around the peripheral portion ofthe cement body and is impregnated with the infusible binder It which isintegrated with the cement body and which impregnates a peripheralportion of the butt i3 of the tuft I4.

It is apparent that other fabric materials, particularly cellulosicmaterials, may be served or wrapped around the cement body in a similarmanner, and soaked with a solution of the ureaformaldehyde condensationproduct before or after wrapping. In this embodiment of the invention itmay be possible to obtain the desired strength and support by the use ofa very small amount of the infusible binder [6 because of the addedstrength furnished by the serving 9 impregnated with the infusiblebinder.

One of the most important aspects of the invention resides in the factthat a brush embodying the invention may be fabricated using aninfusible urea-formaldehyde condensation product as the onlycementitious agent. Thus, the amount of infusible binder used in thepractice of the invention may range from an amount sufiicient toimpregnate a peripheral portion of the butt of the tuft (as described indetail hereinbefore) to the entire amount of cementitious agent used (asdescribed in detail hereinafter). The brushes illustrated in FiguresIII, IV, VII, VIII and X are examples of brushes in which all of thecementitious agent used consists of the infusible binder hereinbeforedescribed.

In Figure IV, thehandle H of the brush illustrated consists ofama-nually grippable-portion 18 at one end and a wedge-shaped portion H9at the other end. A generally hemi-cylindrically-shaped solid resinousbody 20 is mounted on and adheres to a face of the wedge-shaped portionl9. Embedded in the resinous body 20 is the butt 2! of the bristle tuft22 which extends throughout the resinous body 20 and from one endthereof outwardly to form a brush tip 23. The brush illustrated inFigure IV having only one bristle tuft is a special type of brush usedfor drawing extremely fine lines, and although this brush serves toillustrate that the invention embodies brushes containing only onebristle tuft, it is to be understood that for the purposes of thisinvention the number of bristle tufts mounted on the brush is notsignificant other than that any number may be so mounted.

The bristle tuft 22 consists of the camel hair hereinbefore described.The solid resinous body 20 consists of the infusible binder hereinbeforedescribed. The solid resinous body 23 may also consist of a mixture ofthe infusible binder and a cement such as animal glue in the proportionshereinbefore described.

In accordance with the invention the binder is applied to the brushillustrated in Figure IV by substantially the same procedure that hasbeen described for applying the binder to the peripheral portion of thecement body 4 of the brush illustrated in Figures I, II and V exceptthat the solution of urea-formaldehyde condensation product is used tomoisten directly the butt 2| of the tuft 22 and to penetrate therein soas to impregnate the basal portion of each bristle in the tuft 22(instead of impregnating only the peripheral portion of the butt 21 ofthe tuft 22). Thus, the butt 2! of the tuft 22 may be dipped in thesolution or the solution may be used to moisten the butt 2| of the tuft22 which is placed on the face of the wedge-shaped portion 19 of thehandle H.

The brush illustrated in Figure IV is particularly characteristic of thediscovery upon which the instant invention is based. If the solidresinous body 23 shown in the brush illustrated in Figure IV (i. e.,consisting of an infusible ureaformaldehyde condensation product) didnot have the bristles embedded therein, the body 2!! would crack anddisintegrate in drying out. If the solid resinous body 20 in the brushillustrated in Figure IV consisted of, for example, animal glue insteadof the infusible urea-formaldehyde condensation product, the animal gluewould crack and crumble readily during ordinary use of the brush. Butthe body of infusible ureaformaldehyde condensation product havingbristles embedded therein as shown in Figure IV is extremely durable andwater resistant and does not crack or disintegrate as would be expected.

Although the infusible binder may be used in the practice of theinvention alone and without additional support or reenforcement (asshown in Figure IV), in many cases it may be desirable to reenforce theresinous body of infusible binder. Moreover, the solution ofurea-formaldehyde condensation product is particularly advantageous foruse in the fabrication of brushes when the brush is so designed that ithas a ferrule-like end in which the bristles are mounted, since thesolution may be poured and gelled easily and at normal temperatures. Thebrushes illustrated in Figures III, VII, VIII, and X serve todemonstrate the adaptability of the invention to the various types ofbrushes which are now fabricated in the brush making art.

In Figure III, the handle 24 of the brush illustrated has mounted on oneof its ends a seam less metal ferrule 25. One end of the ferrule 25 iscrimped onto the handle 24 and the other end of the ferrule 25 embracesa bristle tuft 26 which extends from the ferrule 25 outwardly to formthe brush tip 21. The butt 28 of the tuft 26 (see Figure VI) extendsinto the ferrule 25 and is embedded in a body of infusible binder 29 inthe recess formed by the walls of the ferrule 25 and the end of thehandle 24. The binder 29 comprises an infusible urea-formaldehydecondensation product as described hereinbefore.

In accordance with the invention, the brush illustrated in Figure IIImay be readily fabricated simply by clamping the ferrule 25 around thebutt 28 of the tuft 26, pouring a small amount of a solution of aurea-formaldehyde condensation product into the open end of the ferrule25 so as to impregnate entirely the basal portion of the bristles in thetuft 26 and then crimping the ferrule 25 (at its open end) to the end ofthe brush handle 24. The urea-formaldehyde condensation product hardensto form the body of infusible binder 29 which is extremely waterresistant and durable.

In Figure VII, the handle 30 of the brush illustrated has a manuallygrippable portion 3! at one end and has mounted at the other end a metalferrule 32. The ferrule 32 is fastened to the handle 20 by means ofsmall rivets 33 piercing one end of the ferrule and the ferrule embracesa body of infusible binder 34 which is set in the recess formed by thewalls of the ferrule 32 and the end of the handle 30. Embedded in theinfusible binder 34 is the butt 33 of the bristle tuft 36 which extendsfrom the ferrule 32 and the infusible binder 34 embraced thereinoutwardly to form the brush tip 31. The binder 34 comprises an infusibleurea-formaldehyde condensation product as described hereinbefore.

In accordance with the invention, the brush illustrated in Figure VIImay be fabricated by first moistening the butt 33 of the tuft 36 with asolution of a urea-formaldehyde condensation product, inserting the butt33 of the tuft 36 in the ferrule 32 and riveting the ferrule 32 to thehandle 30. The urea-formaldehyde condensation product then hardens toform the infusible binder 34 which is extremely resistant to the actionof solvents.

In Figure VIII, the brush illustrated has a hollow quill handle 38. Awire loop 39 wrapped around one end of the quill handle 38 serves tocrimp the quill around the body of infusible binder 40. Embedded in theinfusible binder 40 is the butt 4! of a bristle tuft 42 which extendsfrom the end of the quill handle 38 and the body 'of the infusiblebinder 40 embraced therein outwardly to form the brush tip 43. Theinfusible binder iil comprises an infusible urea-formaldehydecondensation product as described hereinbefore.

In acoordance with the invention, the brush illustrated in Figure VIIImay be fabricated simply by crimping one end of a quill 38 around thebutt 4! of a bristle tuft :12 (by tightening the wire loop 33 around theend portion of the quill-38) and then pouring a small amount of asolution of a ureaformaldehyde condensation product into the open end ofthe quill 38 so as to flow down the inside of the quill 38 and toimpregnate thoroughly the basal portion of the bristles in the tuft 42.The urea-formaldehyde condensation product hardens to form the infusiblebinder 40 which thoroughly 9 impregnates and holds the butt 4| of thetuft 42 in the quill 38.

In Figure X, the handle 44 of the brush illustrated has a manuallygrippable portion 45 at one end and a socket 49 at the other end. Thesocket contains a body of infusible resinous binder 41 (see Figure XI)which adheres to the walls of the socket 46 and has embedded therein thebutt 48 of a bristle tuft 49 which extends from the binder 4'! outwardlyto form the brush ti 50. The binder 41 comprises an infusibleurea-formaldehyde condensation product as described hereinbefore.

In accordance with the invention, the brush illustrated in Figure X maybe fabricated by thoroughly moistening the butt 48 of the tuft 49 in asolution of a urea-formaldehyde condensation product and then placingthe butt 48 in the socket 46 of the handle 44, or by pouring a smallamount of a solution of urea-formaldehyde condensation product into theempty socket 46 in the handle 44 and then stufiing the butt 48 of thetuft 49 in the socket. The urea-formaldehyde condensation producthardens to form the infusible binder 47 which is extremely waterresistant and durable.

The use of a brush handle having a ferrule-like end may be preferred inmany cases in the practice of the invention, and as hereinbefore shown,the ferrule-like end may assume numerous forms. For example, the brushesshown in Figures III and VII have ordinary metal ferrules mounted on oneend of the brush handle. The brush shown in Figure VIII has a hollowhandle so that the ferrule-like end is an integral portion of thehandle.

The brush shown in Figure X has a socket in the ferrule-like end of itshandle and thus the ferrulelike end is also an integral portion of thehandle.

Various modifications of the structure may be made without departingfrom the spirit and scope of the invention.

Having described the invention, I claim:

1. A brush comprising a handle and a tuft having its butt secured tosaid handle, the butt of said tuft being impregnated with animal glueand having only a peripheral layer impregnated with a hardened bindercomprising at least 50 per cent by weight of a hardenedurea-formaldehyde condensation product.

2. A brush as claimed in claim 1 wherein the butt of the tuft comprisesa peripheral layer of a wrapping of a fabric material impregnated withthe hardened binder.

3. A brush as claimed in claim 2 wherein the Wrapping is in the form ofa serving.

4. A brush as claimed in claim 1 wherein the tuft is camel hair.

5. A method of fabricating a brush comprising a handle and a tuft havingits butt impregnated with animal glue and secured to said handle,characterized by the steps of impregnating only a peripheral layer ofthe butt of said tuft with a solution of a binder comprising at least byweight of a urea-formaldehyde condensation product and then causing saidcondensation product to harden.

6. A method as claimed in claim 5 wherein the butt of the tuft issecured to the handle by the addition of a peripheral serving layer andsuch serving layer is then impregnated with the solution.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 686,655 Higgins Nov. 12, 1901 1,556,298 Morck Oct. 6, 19252,015,806 Menger Oct. 1, 1935 2,055,322 Teller Sept. 22, 1936 2,064,949Rolker Dec. 22, 1936 2,133,335 Wilson et al Oct. 18, 1938 2,194,122Krams Mar. 19, 1940 2,202,292 Howard May 28, 1940 2,203,501 Menger June4, 1940 2,310,186 Abrams Feb. 2, 1943 2,311,818 Dawson Feb. 23, 19432,332,802 Leonardson Oct. 26, 1943 2,405,658 Kremer Aug. 13, 19462,417,750 Hall Mar. 18, 1947 FOREIGN PATENTS Number Country Date 408,072Great Britain Apr. 5, 1934 506,358 Great Britain May 26, 1939

